About two hours elapsed between the time of departure and the probable time of the accident. At the recommended cruising speed, the time en route from take-off to the accident site was approximately 15 to 20 minutes. Because there was no communication with any agency or other aircraft after the first eight minutes of flight, the pilot's actions for the duration of the flight could not be determined. However, the observed flight path of the aircraft and the time flown suggest that the pilot persisted with his last known plan to follow the highway and had repeatedly circled back when snow showers were encountered. Reduced visibility due to snow showers and the flat, snow-covered surface of Fox Lake would have produced a uniformly white environment devoid of the visual contrasts that are essential for accurate depth perception. These conditions are known to have existed at the approximate time and location of the accident. It is therefore probable that the pilot encountered whiteout conditions and was unable to accurately judge, through visual reference, his altitude above the surface of the lake. In the absence of a visible horizon, the pilot might also have succumbed to spatial disorientation,(4) particularly if he initiated a turn to escape the deteriorating weather. The pilot's lack of instrument training and experience would have made him more susceptible to the effects of whiteout and spatial disorientation. The damage to the propeller indicates that the engine was developing considerable power at impact, while the length of the wreckage trail indicated considerable speed. The wreckage pattern and the damage characteristics indicate that the aircraft struck the ground in a steep, left bank and a shallow, nose-down attitude, with the landing gear and flaps retracted. It therefore appears that the aircraft was operating at cruise speed in cruise configuration when it struck the surface of Fox Lake.Analysis About two hours elapsed between the time of departure and the probable time of the accident. At the recommended cruising speed, the time en route from take-off to the accident site was approximately 15 to 20 minutes. Because there was no communication with any agency or other aircraft after the first eight minutes of flight, the pilot's actions for the duration of the flight could not be determined. However, the observed flight path of the aircraft and the time flown suggest that the pilot persisted with his last known plan to follow the highway and had repeatedly circled back when snow showers were encountered. Reduced visibility due to snow showers and the flat, snow-covered surface of Fox Lake would have produced a uniformly white environment devoid of the visual contrasts that are essential for accurate depth perception. These conditions are known to have existed at the approximate time and location of the accident. It is therefore probable that the pilot encountered whiteout conditions and was unable to accurately judge, through visual reference, his altitude above the surface of the lake. In the absence of a visible horizon, the pilot might also have succumbed to spatial disorientation,(4) particularly if he initiated a turn to escape the deteriorating weather. The pilot's lack of instrument training and experience would have made him more susceptible to the effects of whiteout and spatial disorientation. The damage to the propeller indicates that the engine was developing considerable power at impact, while the length of the wreckage trail indicated considerable speed. The wreckage pattern and the damage characteristics indicate that the aircraft struck the ground in a steep, left bank and a shallow, nose-down attitude, with the landing gear and flaps retracted. It therefore appears that the aircraft was operating at cruise speed in cruise configuration when it struck the surface of Fox Lake. The pilot continued his visual flight rules flight in adverse weather conditions but was not qualified, trained, or sufficiently experienced to do so. The flat, snow-covered surface of Fox Lake and the presence of snow showers at the approximate time and location of the accident were conducive to whiteout conditions. The pilot flew the aircraft into the frozen surface of Fox Lake, probably because whiteout conditions degraded his ability to see the aircraft's altitude and orientation.Findings as to Causes and Contributing Factors The pilot continued his visual flight rules flight in adverse weather conditions but was not qualified, trained, or sufficiently experienced to do so. The flat, snow-covered surface of Fox Lake and the presence of snow showers at the approximate time and location of the accident were conducive to whiteout conditions. The pilot flew the aircraft into the frozen surface of Fox Lake, probably because whiteout conditions degraded his ability to see the aircraft's altitude and orientation. The weather forecast received by the pilot did not predict visibilities below six statute miles in snow showers. The actual visibility dropped to one-half statute mile in the showers.Other Findings The weather forecast received by the pilot did not predict visibilities below six statute miles in snow showers. The actual visibility dropped to one-half statute mile in the showers.